ATMEGA329 查看數據表（PDF） - Atmel Corporation

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ATMEGA329

8-bit Microcontroller with In-System Programmable Flash

Atmel Corporation 

ATmega329/3290/649/6490

35.2 ATmega3290

35.2.1

ATmega3290 rev. C

• Interrupts may be lost when writing the timer registers in the asynchronous timer

1. Interrupts may be lost when writing the timer registers in the asynchronous timer

If one of the timer registers which is synchronized to the asynchronous timer2 clock is writ-

ten in the cycle before a overflow interrupt occurs, the interrupt may be lost.

Problem Fix/Wortkaround

Always check that the Timer2 Timer/Counter register, TCNT2, does not have the value 0xFF

before writing the Timer2 Control Register, TCCR2, or Output Compare Register, OCR2.

35.2.2

ATmega3290 rev. B

Not sampled.

35.2.3

ATmega3290 rev. A

• LCD contrast voltage too high

• Interrupts may be lost when writing the timer registers in the asynchronous timer

1. LCD contrast voltage too high

When the LCD is active and using low power waveform, the LCD contrast voltage can be too

high. This occurs when VCC is higher than VLCD, and when using low LCD drivetime.

Problem Fix/Workaround

There are several possible workarounds:

- Use normal waveform instead of low power waveform

- Use drivetime of 375 µs or longer

2. Interrupts may be lost when writing the timer registers in the asynchronous timer

If one of the timer registers which is synchronized to the asynchronous timer2 clock is writ-

ten in the cycle before a overflow interrupt occurs, the interrupt may be lost.

Problem Fix/Wortkaround

Always check that the Timer2 Timer/Counter register, TCNT2, does not have the value 0xFF

before writing the Timer2 Control Register, TCCR2, or Output Compare Register, OCR2.

2552J–AVR–08/07

381

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